This is level 8 of the New Tunnel.
In this level, since the ceiling is quite low, you can easily jump onto the ceiling if you use the Duplicator. This sometimes may help you, or bring you the unexpected, so please be careful.
If you use the Child, also look out for the ceiling. You can do the high jump and float, try to land on a farther platform. Repeat for a few times and you will pass this level.